Isomerization processes are commonly used within the petrochemical and petroleum refining industry for converting linear olefins to more valuable branched olefins, which may further be hydrogenated to high-octane paraffins.
U.S. Pat. No. 3,749,752 discloses a gas-phase olefin hydroisomerization process where short C4-C9 olefins, typically obtained as refinery offstreams, are simultaneously hydrogenated and hydroisomerized to branched paraffins having more branched carbon skeleton than the precursor olefin. Said process is carried out in the presence of a catalyst containing a platinum group metal, a rhenium component, alumina and mordenite, at a temperature of 0-500° C. and under a pressure of 0-200 atm.
US 2004/0210098 provides a process where C4-C6 monoolefins and terminal double bonds containing α-olefins are isomerized to the corresponding monoolefins having internal bouble bonds and simultaneously any polyunsaturated olefins present are selectively hydrogenated to monoolefins and isomerized to the corresponding monoolefins having internal bouble bonds, in the presence of at least one added sulfur compound and a catalyst comprising transition group VIII element, such as palladium on a support, such as alumina.
A process for preparing isomerized linear olefins is presented in WO 95/21225, where C12-C24 olefins are skeletally isomerized over a catalyst comprising an intermediate pore size molecular sieve, with or without Group VIII metal under skeletal isomerization conditions without hydrogen to yield olefins particularly suitable as drilling fluids. If desired, the obtained olefins may subsequently be hydrogenated as a second step to yield corresponding paraffins.
Often isomerization of higher olefins is associated with cracking to smaller components and with oligomerization because relatively high reaction temperatures and pressures are needed, typically resulting in the decrease of yields and in the deactivation of the isomerization catalyst. Isomerization catalysts containing mordenite usually lead to cracking to smaller components. Additionally, when the hydrogenation is carried out as another separate process step, separate equipment for the isomerization and hydrogenations steps are required, whereby the lead-time is longer and investment costs higher.
So far there are no commercial methods available where heavier olefins having at least 10 carbon atoms are simultaneously isomerized and hydrogenated. Typically heavier olefins are first hydrogenated to yield paraffins, which are subsequently isomerized. This method requires separate reactors for each step and high isomerization temperatures consuming high amounts of energy.
Based on the above it can be seen that there is an evident need for an improved and simplified method for the manufacture of branched saturated hydrocarbons from heavier olefins having at least 10 carbon atoms, particularly as heavier olefins having at least 10 carbon atoms provide a potential source for alternative starting material for branched saturated hydrocarbons.